1. Field of the Invention
The present invention relates to an ultrasound diagnosis apparatus, and in particular to a technique for supporting a probe operation (position and/or orientation adjustment) by a user.
2. Description of the Related Art
An ultrasound diagnosis apparatus has a function to display, on a screen of a display device, “a body mark (body symbol)” and a “probe mark (probe symbol)” as reference images along with an ultrasound image (image of living tissue, or living body image). The body mark is typically a simple, two-dimensional figure schematically representing a partial shape within a living body. A user may operate the device to select a specific body mark corresponding to a body part to be diagnosed using ultrasound from among a plurality of body marks which are prepared in advance. The body mark is displayed near the living body image. In order to identify a position and direction of the probe during ultrasound diagnosis, a probe mark is displayed overlapping the body mark. The probe mark is typically a figure of a simple line or simple box. The user can freely set the position and direction of the probe mark on the body mark. These marks are important information for identifying the part for which the living body image is obtained, on the display screen or in an examination report.
In order to evaluate progress of a disease and status of healing, comparative observation of a past ultrasound image and a current ultrasound image for a same patient is performed. During this process, it is necessary to match, to the highest possible degree, the current position and the current orientation of the probe with the past position and the past orientation of the probe corresponding to the time when the past ultrasound image is obtained, because it is necessary to perform the current ultrasound diagnosis with respect to a same part as the part to which the past ultrasound diagnosis is applied. For this purpose, a two-screen display function provided in the ultrasound diagnosis apparatus is utilized. For example, a past ultrasound image is displayed on the left half of the display screen and a current ultrasound image is simultaneously displayed on the right half of the display screen. The user operates the probe while comparatively observing both images so that the content of the current ultrasound image becomes closer to the past ultrasound image. In this manner, it is possible for the user to find an appropriate position and an appropriate orientation of the probe in the current ultrasound examination through a trial and error process.
Japanese Patent Laid-Open Publication No. 2000-201926 discloses an apparatus in which a three-dimensional body mark and a three-dimensional probe mark are displayed. In this apparatus, when a user changes a position of a probe mark, display content of a body mark is automatically changed so that the position of the probe mark is at a center position of the body mark. Japanese Patent Laid-Open Publication No. 2001-017433 also discloses an apparatus in which a three-dimensional body mark and a three-dimensional probe mark are displayed. In this apparatus, a body mark and a probe mark seen from a viewing direction designated by the user using an input unit are generated. A probe mark is displayed on an appropriate position on a body mark based on an actual positional relationship between a living body and the probe. In this case, the actual positional relationship is measured using a magnetic sensor (refer to paragraph 0025 of Japanese Patent Laid-Open Publication No. 2001-017433).
None of the references, however, discloses a technique for supporting a probe operation to match the current diagnosis part to the past diagnosis part.
Generally, users, such as a physician, an ultrasound examination technician, or the like, require significant experience to operate the probe to quickly and precisely match the current diagnosis part to the past diagnosis part. In addition, even for an expert user, the probe operations are complex. Further, even for an expert user, the optimum probe position and the optimum probe orientation may not be easily found. In particular, when the user during the past ultrasound diagnosis differs from the user in the current ultrasound diagnosis, these problems become more significant. When the diagnosis part of the past and the diagnosis part of the current differ, there is a problem in that an accurate diagnosis is not possible. This problem occurs because of a deviation of the probe position, deviation of the probe orientation, or both. Therefore, in order to prevent or reduce these problems, a support for the probe operations is desired.